In U.S. Pat. No. 4,209,568, a water-impervious panel is disclosed which comprises a water permeable support sheet such as a corrugated paperboard sheet on a surface of which is applied a gelled bentonite composition. The open-faced side of the panel is adapted to be pressed against a structure to secure the panel in place thereby providing a waterproof barrier.
In U.S. Pat. Nos. 3,186,896, 4,048,373, 4,103,499 and 4,139,588 moisture impervious panel constructions are disclosed, each of which employs a corrugated paperboard carrier for a water-swellable bentonite, or a sealant composition which incorporates a water-swellable bentonite as a principal component. The panels serve as water barriers for foundations and other in-ground installations.
While the panel constructions of the afore-mentioned patents function as seepage resistant structures, they have a number of shortcomings. Thus, for example, the use of a gelled bentonite composition as disclosed in U.S. Pat. No. 4,209,568 presents shipping and handling problems due to the generally paste-like character of the gel. The filled corrugated paperboard panels shown in the othr patents mentioned above utilize a relatively thin corrugated paperboard carrier which places undesirable restrictions on the amount of water-swellable material per unit area of the panel, a condition which can adversely affect the ability of the panels to provide adequate protection against seepage. In this same connection, the particle size of the water-swellable material loaded into the paperboard carrier must be carefully monitored to prevent, in the case where the particles are too coarse, the formation of voids, or, in the case where the material is too powdery, the formation of area of low density of the water-swellable material. A still further shortcoming of such filled corrugated paperboard panels is their rigid, comparatively inflexible construction, a property which essentially precludes bending the panels around corners, or conforming them to rounded or curved surfaces. This property of the panels also presents a problem when the margins of two, or more, adjacent panels are positioned in overlapping relation to each other.
The overlaps leave substantial air gaps which readily fill with water and act as pathways enabling water to reach the surface to be protected by the panels. The rigid, inflexible character of the panels also requires that they be cut, as by sawing, to enable them to be properly fitted on a surface to insure complete coverage. Sawing of the panels along, or transversely of, the water-swellable material containing flutes of the corrugated paperboard carrier results in the escape of a portion of the water-swellable material thereby leaving areas of the surface against which the sawed panels are positioned unprotected.